Disclosed herein is a method comprising: depositing a first amount of electric charges into a region of a sample, during a first time period; depositing a second amount of electric charges into the region, during a second time period; while scanning a probe spot generated on the sample by a beam of charged particles, recording from the probe spot signals representing interactions of the beam of charged particles and the sample; wherein an average rate of deposition during the first time period and an average rate of deposition during the second time period are different.